[I like to know things.]

Hi my name is Chrystal. I graduated from Texas – university with the degree in agriculture leadership and development, with emphasis in genetics and biochemistry. I also researched in several labs on campus in genetics, and today I’m going to talk about some very interesting facts about genetics that you probably don’t know.

Now you probably think that the human genome size is rather large, which, it is because we are very complex mammal.  In fact, it will fill up 90 volumes of an encyclopedia Britannica.

Now, why don’t we compare that to something else. Let’s say, a lily seed. A lily seed actually is bigger than our genome. Its genome will fill 1800 volume of the encyclopedia Britannica.

Now, we normally think that the human genome is this huge vast information but actually if we convert it to binary code, the human genome is just slightly larger than that of the storage capacity of a CD ROM. As a matter of fact, Windows XP is twice as large as our human genome. So, the human genome requires 750 MB of storage whereas Windows XP would require 1500 MB of storage. So, as you can see, Windows XP actually requires twice the storage as the human genome.

In computer terms, the human genome is stored in 6 bit combinations of information. The Playstation III is a 128 bits.

Now something really interesting is that the puffer fish (isn’t it adorable?), actually has no junk DNA, which is interesting because humans are actually made up of 95% junk DNA. So, there are organisms out there that don’t have any junk DNA, whatsoever.

Well one thing that researchers are particularly interested in is finding out what is junk DNA and does it actually do anything? One reason study suggest that it really just it. Researchers took 2.3 million letters of DNA out of a mouse and compared it to a mouse with full link version of DNA and found out there are no differences whatsoever.

So far, we’ve talked about the human genome size. Well now, we gonna talk about the actual number of genes that we have in our genome. A gene is actually just a section of our overall genome that helps the body to know how the code calls for specific proteins within our body. So now we gonna talk about how many genes you have compared to number of genes that other organisms have.

Now, when scientist first started to study genetics and the human genome, we actually expected to find 3x more the number of genes that we actually found which is rather interesting because the 20,000 – 25, 000 genes that we did find is only about twice the number that a round worm has. And in fact, there’s a variety of an amoeba that has 200x the number of genes that a human being has.

Now when scientist first started studying the human genome, we thought that each gene coded for one protein. But actually, we have about 250,000 proteins being coded by 25,000 different genes which means that each gene is coding for approximately 10 proteins. And scientists have no idea how this occurs.

Now human beings, we always consider our selves pretty complex compared to other organisms, but if we compare ourselves to coral, we actually have approximately the same number of genes as coral does.

Now you’re probably thinking, “I’m a human. I have to have a ton of genes.” And, we do. We have 20,000-25,000 genes. But you know what, a grain of rice actually has 40,000-50,000 genes. Can you imagine a little grain of rice has 50,000 genes and we have 25,000? What’s up with that?

As a matter of fact, many plants actually have more genes and much more complex genome than many complex mammals.

• Now firefly has about 13,500 genes.
• A nematode is gonna have about 20,000.
• A human has in between 20,000-25,000 genes.
• A puffer fish has approximately 21,000 genes.
• Then we get to tail crest which has right about 25,500 genes.
• And then rice actually has 40,000 – 50,000 genes.
• And in fact, there’s a variety of an amoeba that has 200x the number of genes (4,000,000) that a human being has.

The smallest genome for a true living organism that is capable of reproduction is actually just 1.4 million based pairs.

So now we gonna talk about the similarities of our gene compared to the genes of other organisms.

• Genes code for proteins and as you can imagine what our bones are made of is probably gonna be pretty similar to the bones of chimpanzees and, even say, fish. So our genes compared to, say a chimpanzee, is approximately 98% similar. We have about 98% of the same genes as the chimpanzees have.
• Now, what you may not know is that we are actually really similar to mice as well. In fact, 75% of our gene are in common with mice.
• Now, let’s look at a dog. A dog’s genetic sequence is actually about 85% similar to a human being’s genetic sequence.
• Now let’s think about sea urchins. They’re small, they’re spiny, no bones. They don’t really look anything like us, do they? Well, actually, compared to the human genes, they have 7,000 genes in common with us which is approximately a quarter (25%) of all of our genes.
• Now if you remember, I mentioned that humans have in between 20,000-25,000 genes.  Now let’s think about how many unique genes they have compared to mice. Humans have actually 300 unique genes that mice don’t have. So out of the 25,000 genes that we have, only 300 are not found in mice.
• Now there are 113 genes that have been transferred from bacteria. Can you imagine, bacteria! A 113 of our genes are from bacteria.

There are about 250 unique human genes that are not found in any lower species. In fact, scientist have not been able to find any evolutionary basis for these genes.

So for centuries, we thought that heredity passes through your blood. You hear the terms, “bloodline”, “mix blood”, “royal blood”. But actually, your blood is the only thing that doesn’t carry DNAs – not passed along.  It doesn’t carry DNA because it’s the only cell in your body that doesn’t carry any nuclei.

Now, surprisingly enough, genetically speaking, all races are equal. As a matter of fact, if you take a random sample of someone’s DNA, just by looking at it, you cannot tell whether they are African-American, Caucasian, Asian, or any other race.

Now we all heard about the human genome project but I bet you didn’t know how much it cost! Since it begin in 1990, the human genome project actually cost $3,000,000,000.

Now if you look back as recently as the 1980s, you’ll see that there is a rush to find a single gene that would explain schizophrenia, intelligence, disposition to violence, homosexuality, and obesity. But since then, no single gene has been found. We now call these characteristics, multi-factorial, which means that it’s a complex interaction of genes that are also affected by the environment. So despite what you hear form the media, there’s no gay gene, no IQ gene, not even a fact gene. In fact, no behavioral characteristic has ever been found to be a result of a single gene.

For about a hundred years now, we’ve been trying to link mental health disorder to genetics. First we started with hereditary studies and back in the 80’s we tried to link one single gene to mental health disorder but now we consider it multi-factorial – meaning that a combination of genetic interactions with environmental triggers – is what could explain mental health disorders. However, scientist have never been able to find a combination of genes with the environmental trigger to explain them into health disorder.

For example, many people think that ADHD is a multi-factorial genetic disease. However, scientist has never been able to find a combination of genes with an environmental factor that accounts for ADHD.

2 Responses to “How Big is Your Genome? Strange DNA”

1. 
   SimonB Says:
   December 15th, 2009 at 3:29 am

   You say here that the human genome would fill 90 volumes of the Encyclopedia Britannica, which is about three times the actual number of volumes in the set, but then you say that the human genome can be stored in just 750 megabytes.

   I am having trouble reconciling these values, can you elaborate on them for me?

2. 
   admin Says:
   July 30th, 2010 at 1:19 am

   This means that 90 volumes of Encyclopedia information can be stored in just 750mb by DNA, while current Technology(eg. memory chip/super computer) cannot store so much information in 750 mb.

   _____________________________
   You say here that the human genome would fill 90 volumes of the Encyclopedia Britannica, which is about three times the actual number of volumes in the set, but then you say that the human genome can be stored in just 750 megabytes.

   I am having trouble reconciling these values, can you elaborate on them for me?

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